The field of enzymatic detergent additives has been rapidly growing during the last decades. Reference is made to the article "How Enzymes Got into Detergents", vol. 12, Developments in Industrial Microbiology, a publication of the Society for Industrial Microbiology, American Institute of Biological Sciences, Washington, D.C. 1971, by Claus Dambmann, Poul Holm, Villy Jensen and Mogens Hilmer Nielsen, to the article "production of Microbial Enzymes", Microbial Technology, Sec. ed., Vol. I, Academic Press, 1979, pages 281-311, by Knud Aunstrup, Otto Andersen, Edvard A. Falch and Tage Kjaer Nielsen, and to Pl.N. Christensen, K. Thomsen and S. Branner: "Development of Detergent Enzymes", a paper presented on Oct. 9, 1986, at the 2nd World Conference on Detergents held in Montreux, Switzerland.
The most common enzymatic detergent additive is a proteolytic additive, but also amylolytic, cellulolytic, and lipolytic detergent additives are suggested, e.g., in GB patent No. 1 554 482, BE patent No. 888 632, and U.S. Pat. No. 4,011,169, column 4, line 65 to column 5, line 68. The above list of enzymes is not exhaustive, but represents the most common enzymatic detergent additives.
Enzymatic detergent additives for use in powder detergents are usually prepared in the form of dust-free granulates. These granulates can be produced in several different ways. Reference can be made to GB patent No. 1 362 365 which describes the production of enzyme containing granulates used as detergent additives by means of an apparatus comprising an extruder and a spheronizer (sold as MARUMERIZERR), and to U.S. Pat. No. 4 106 991, which describes the production of enzyme containing granulates used as detergent additives by means of a drum granulator. Reference is also made to European patent publication EP-A No. 0170360 which describes enzyme granulates containing certain salts to improve the storage stability.
Whereas enzyme granulates prepared according to known methods are entirely satisfactory for use in many commercial powder detergents, enzyme stability of these granulates is reduced in certain detergent formulations and at certain storage conditions. These include particularly detergents with high water content and/or high pH and/or high content of bleaching agents and particularly by storage at high humidity and temperature.
In FR patent No. 2.058.421 a method for production of detergent or bleaching agents containing enzymes protected with a coating of an enteric coating agent is described. However, the inventor hereof has shown that the protective effect, i.e., the improvement of enzymatic stability, is variously absent, very small or even negative, probably due to the fact that the particle size of the powder is too small in comparison to the (small) amount of coating agent used, and the coating agent is not coated on the powder in an optimal manner. Also, the method involves the use of a solution of the coating agent in an organic solvent.
Thus, a need exists for an easier and more efficient method for production of a particulate detergent enzyme product which is modified in such manner that the enzymatic stability is improved considerably in adverse detergent formulations and/or at adverse storage conditions, whereby this modification in no regard should impair any process or material related to the continued storage and later use of the product.